Affinity binding assays are often used to detect the presence of a molecule associated with a disease condition or biological state. These assays are based upon binding pairs, a pair of molecules which exhibit mutual affinity or binding capacity. Typically, one of the molecules of the binding pair is designated the ligand and one of the molecules of the binding pair is designated the antiligand, receptor, analyte or target. The designation is arbitrary in the sense that it depends on which molecule one wants to detect. The binding pair may comprise two complementary nucleic acids, antigens and antibodies, drugs and drug receptor sites, and enzymes and enzyme substrates.
Typically, one member of the biological binding pair is immobilized on a solid surface such as plastic, glass or nitrocellulose paper. A sample, potentially containing the molecule of interest, is applied to the solid support. After a period of incubation, in which the molecule of interest has an opportunity to bind to the immobilized ligand, the unbound sample is removed. During this period of incubation the sample and support are rocked to create a current of fluid over the support to maximize the opportunity of target molecules to be received by the immobilized ligand. The target, if present, forms a complex with the immobilized ligand.
Next, additional reagents are applied to the support which reagents are capable of reacting with the complex formed or the target captured by the immobilized ligand. These further reagents typically includes a labeled second ligand, which second ligand is capable of binding to the target or the complex. A labeled second ligand has a label, a molecular moiety capable of detection. Typical labels include by way of example, without limitation, radioactive isotopes, enzymes, luminescent agents, precipitating agents and dyes.
The support is monitored in the presence of appropriate signal generating conditions for the presence of signal. The signal is indicative of the presence of the target.
Methods to immobilize immunological agents, peptides and nucleic acid on a solid support are well known in the art. Nucleic acid sequences specific for a particular disease state are commonly reported in the scientific press, U.S. and foreign patents and published applications and various databank for nucleic acid sequence information. Immunological agents such as antibodies specific for a particular organism or disease states are also reported in the scientific press, U.S. and foreign patents and published patent applications, scientific catalogs of chemical suppliers (such as Sigma Chemical Company of St. Louis, Mo., U.S.A.), and with respect. to cell-lines maintained by depositories (such as The American Type Culture Collection of Rockville, Md., U.S.A.).
The performance of affinity assays has been limited due to the need to manually apply and remove reagents to detect the presence of the analyte. Affinity assays are typically performed in cuvettes, small test tube-like vessels. The small volumes and openings of cuvettes are awkward and can lead to operator error.
Although aspects of the process have been automated, there remains a need for a containment vessel that allows substantially the entire assay to be run in an automated fashion. There remains a need for a vessel to facilitate the application and removal of fluids and to permit the incubation of the sample and immobilized ligands in a consistent manner.